日期:2018年4月8日


帮你脱离鼠标的小工具


注意:仅限win7系统
ALTRun
Alt+R启动
快捷先中打开项
支持自定义打开项,例如.m2文件夹

简单实现SpringMVC


1.新建maven项目
2.到pom中添加servlet依赖
<groupId>com.justin.springmvc</groupId>
    <artifactId>springmvc</artifactId>
    <version>1.0-SNAPSHOT</version>

    <packaging>war</packaging>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.0.1</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

</project>

3.新建web.xml文件(src下main下webapp下WEB-INF下)
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://java.sun.com/xml/ns/javaee"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
            http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
         version="3.0">
    <servlet>
        <servlet-name>MySpringMVC</servlet-name>
        <servlet-class>com.justin.servlet.MyDispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>application.properties</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>MySpringMVC</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
</web-app>

4.新建application.properties文件(resources下)
配置待扫描的包
scanPackage=com.justin.core

5.新建包com.justin.annotation
6.创建自己的controller注解
package com.justin.annotation;

import java.lang.annotation.*;

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface MyController {

    /**
     * 给MyController注册别名
     *
     * @return 别名
     */
    String value() default "";
}
7.创建自己的MyRequestMapping注解
package com.justin.annotation;

import java.lang.annotation.*;

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface MyRequestMapping {

    /**
     * 访问该方法的url
     *
     * @return url
     */
    String value() default "";
}
8.创建自己的MyRequestParam
package com.justin.annotation;

import java.lang.annotation.*;

@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface MyRequestParam {

    /**
     * 参数的别名,必填
     *
     * @return 别名
     */
    String value();
}
9.新建com.justin.servlet包
10.新建MyDispatcherServlet
package com.justin.servlet;

import com.justin.annotation.MyController;
import com.justin.annotation.MyRequestMapping;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.net.URL;
import java.util.*;

public class MyDispatcherServlet extends HttpServlet {

    private Properties properties = new Properties();

    private List&lt;String&gt; classNames = new ArrayList&lt;&gt;();

    private Map&lt;String, Object&gt; ioc = new HashMap&lt;&gt;();

    private Map&lt;String, Method&gt; handlerMapping = new HashMap&lt;&gt;();

    private Map&lt;String, Object&gt; conntrollerMap = new HashMap&lt;&gt;();

    @Override
    public void init(ServletConfig config) throws ServletException {
        //加载配置文件
        doLoadConfig(config.getInitParameter("contextConfigLocation"));
        //2.初始化所有相关联的类,扫描用户设定的包下面所有的类
        doScanner(properties.getProperty("scanPackage"));
        //3.拿到扫描到的类,通过反射机制,实例化,并且放到ioc容器中(k-v  beanName-bean) beanName默认是首字母小写
        doInstance();
        //4.初始化HandlerMapping(将url和method对应上)
        initHandlerMapping();
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        try {
            //处理请求
            doDispatch(req, resp);
        } catch (Exception e) {
            resp.getWriter().write("500!! Server Exception");
        }
    }

    private void doDispatch(HttpServletRequest req, HttpServletResponse resp) throws Exception {
        if (handlerMapping.isEmpty()) {
            return;
        }
        String url = req.getRequestURI();
        String contextPath = req.getContextPath();

        url = url.replace(contextPath, "").replaceAll("/+", "/");

        if (!this.handlerMapping.containsKey(url)) {
            resp.getWriter().write("404 NOT FOUND!");
            return;
        }

        Method method = this.handlerMapping.get(url);

        //获取方法的参数列表
        Class&lt;?&gt;[] parameterTypes = method.getParameterTypes();

        //获取请求的参数
        Map&lt;String, String[]&gt; parameterMap = req.getParameterMap();

        //保存参数值
        Object[] paramValues = new Object[parameterTypes.length];

        //方法的参数列表
        for (int i = 0; i &lt; parameterTypes.length; i++) {
            //根据参数名称做某些处理
            String requestParam = parameterTypes[i].getSimpleName();

            if (requestParam.equals("HttpServletRequest")) {
                //参数类型已明确,这边强转类型
                paramValues[i] = req;
                continue;
            }
            if (requestParam.equals("HttpServletResponse")) {
                paramValues[i] = resp;
                continue;
            }
            if (requestParam.equals("String")) {
                for (Map.Entry&lt;String, String[]&gt; param : parameterMap.entrySet()) {
                    String value = Arrays.toString(param.getValue()).replaceAll("\\[|\\]", "").replaceAll(",\\s", "");
                    paramValues[i] = value;
                }
            }
        }
        //利用反射机制来调用
        try {
            //第一个参数是method所对应的实例 在ioc容器中
            method.invoke(this.conntrollerMap.get(url), paramValues);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void doLoadConfig(String location) {
        //把web.xml中的contextConfigLocation对应value值的文件加载到流里面
        InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream(location);
        try {
            properties.load(resourceAsStream);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (null != resourceAsStream) {
                try {
                    resourceAsStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private void doScanner(String packageName) {
        //把所有的,替换成/
        URL url = this.getClass().getClassLoader().getResource("/" + packageName.replaceAll("\\.", "/"));
        File dir = new File(url.getFile());
        for (File file : dir.listFiles()) {
            if (file.isDirectory()) {
                doScanner(packageName + "." + file.getName());
            } else {
                String className = packageName + "." + file.getName().replace(".class", "");
                classNames.add(className);
            }
        }
    }

    private void doInstance() {
        if (classNames.isEmpty()) {
            return;
        }
        for (String className : classNames) {
            try {
                //把类搞出来,反射来实例化(只有加@MyController需要实例化)
                Class&lt;?&gt; clazz = Class.forName(className);
                if (clazz.isAnnotationPresent(MyController.class)) {
                    ioc.put(toLowerFirstWord(clazz.getSimpleName()), clazz.newInstance());
                } else {
                    continue;
                }
            } catch (Exception e) {
                e.printStackTrace();
                continue;
            }
        }
    }

    private void initHandlerMapping() {
        if (ioc.isEmpty()) {
            return;
        }
        try {
            for (Map.Entry&lt;String, Object&gt; entry : ioc.entrySet()) {
                Class&lt;? extends Object&gt; clazz = entry.getValue().getClass();
                if (!clazz.isAnnotationPresent(MyController.class)) {
                    continue;
                }
                //拼url时,是controller头的url拼上方法上的url
                String baseUrl = "";
                if (clazz.isAnnotationPresent(MyRequestMapping.class)) {
                    MyRequestMapping annotation = clazz.getAnnotation(MyRequestMapping.class);
                    baseUrl = annotation.value();
                }
                Method[] methods = clazz.getMethods();
                for (Method method : methods) {
                    if (!method.isAnnotationPresent(MyRequestMapping.class)) {
                        continue;
                    }
                    MyRequestMapping annotation = method.getAnnotation(MyRequestMapping.class);
                    String url = annotation.value();

                    url = (baseUrl + "/" + url).replaceAll("/+", "/");
                    handlerMapping.put(url, method);
                    conntrollerMap.put(url, clazz.newInstance());
                    System.out.println(url + "," + method);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 把字符串的首字母小写
     *
     * @param name 代转字符串
     * @return 转出结果
     */
    private String toLowerFirstWord(String name) {
        char[] charArray = name.toCharArray();
        charArray[0] += 32;
        return String.valueOf(charArray);
    }
}
11.新建com.justin.core.controller
12.新建TestController
package com.justin.core.controller;

import com.justin.annotation.MyController;
import com.justin.annotation.MyRequestMapping;
import com.justin.annotation.MyRequestParam;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@MyController
@MyRequestMapping("/test")
public class TestController {

    @MyRequestMapping("/doTest")
    public void test1(HttpServletRequest request, HttpServletResponse response, @MyRequestParam("param") String param) {
        System.out.println(param);
        try {
            response.getWriter().write("doTest method success! param:" + param);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @MyRequestMapping("/doTest2")
    public void test2(HttpServletRequest request, HttpServletResponse response) {
        try {
            response.getWriter().println("doTest2 method success!");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
13.大功告成,通过tomcat或jetty启动项目
14.访问localhost:8080/test/doTest?param=justin
15.没报异常错误则说明构建成功,否则请根据异常自行检查!